CD8A and rheumatoid arthritis: Multivariate analysis established two models: Model 1 (age, BMI, disease duration, ESR, RF) and Model 2 (CRP, IL-6, TNF-α, CD4+, CD8+, CD4+/CD8+, HMGB1) and the analysis results indicated that ESR, RF, IL-6, CD4+, CD4+/CD8+, and HMGB1 were factors associated with active RA.